Method and apparatus for tilting a mast



Nov. 14, 1961 w. K. THORSON 4 METHOD AND APPARATUS FOR TILTING A MASTFiled March 19, 1956 2 Sheets-Sheet 1 ll llllllnum. l Hum."

30 b t AH -L. 'm%z #6 Nov. 14, 1961 w. K. THORSON 3,008,549

METHOD AND APPARATUS FOR TILTING A MAST Fi led March 19, 1956 2Sheets-Sheet 2 ff V\ A. Tho/"Jan IN V EN TOR.

ATTOR/V' VJ United States Patent 3,008,549 METHOD AND APPARATUS FORTILTING A MAST Warren K. Thorson, Dallas, Tex., assignor, by mesneassignments, to Dresser Industries, Inc., Dallas, Tex., a corporation ofDelaware 7 Filed Mar. 19, 1956, Ser. No. 572,456

6 Claims. (Cl. 189-45) This invention relates to improvements in thehandling of equipment laterally of a well location during the drillingof and performance of other operations on a'well, particularly at anoffshore or other water location. one of its aspects, it relates to amast for suspending equipment above a well in connection with thedrilling thereof and performance of other operations thereon, and amethod of using same which obviates the need for barge-mounted cranesconventionally employed at offshore locations for handling wellequipment and the like laterally of the well.

In the drilling of offshore wells, it is common practice to convey amast to the well location upon a floatable barge-mounted support. At thedesired location the barge is submerged or the support otherwise fixedlylocated with respect to the subsurface level to provide a firmfoundation for the mast. Themast is then properly positioned overarr-open space inwardly of a side of the support and above the welllocation, which space is known as a drilling slot." When so positioned,the mast may be used for suspending equipment above the well locationrtodrill same and to perform other operations thereon, such as thecompletion of the well. In connection with such operations, it isnecessary to set various items ofequipment, such as wellhead protectivejackets and production platforms, at the welllocations.

For this purpose, it has been the practice to use, floatablebarge-mounted cranes adjacent the mast support to lift the equipmentfrom a position laterally of the well location for placement'over thewell. However, the use of such cranes is normally quite expensive. Forexample, they may cost as much. as $8,000 to $10,000 a day, and the wellmay be so located as to require up to two weeks in travel time from thehome port. Also, the floating barges are at the mercy of weatherconditions and cannot operate in rough weather.

It is, therefore, an object of this invention to use a mast of the typegenerally employed in the drilling of and performing of other operationson a well as a crane boom for handling equipment laterally of the welllocation and, in the case of offshore wells, laterally of the fixedsupport for the mast.

A more particular object is to provide a novel method of converting amast of this type from an upright position for suspending equipmentabove the well location to a tilted position for handling equipmentlaterally of the well location, in which tilted position there will besubstantially no eccentric loading on the boom due to combined bendingand compression forces.

Another object is to provide a mast construction in which theconventional hoisting means for the mast may 3,008,549 Pat'ented Nov. 14, 1961 "ice location; and, more particularly, further improvementswhich enable the use of such a mast as a crane boom with a mini-mum ofstructural modifications;

Yet another object is to provide in a mast of type described in theforegoing object, such improvements which enable the means for raisingthe mast to be further used in swinging it between upright and tiltedpositions. Other objects, advantages and features of this invention willbe apparent to one skilled in the art upon a consideration of thewritten specification, the attached claims and the annexed drawings.

In the drawings, wherein like reference characters are used throughoutto designate like parts:

'FIG. 1 is a side elevation of a mast embodying the features of thepresent invention which is mounted upon a platform at an olfshorelocation, and shown in a substantially horizontal position such as itmay assume during conveyance to and from the offshore location;

FIG. 2 is a side elevation similar to FIG. 1, but in which the mast hasbeen raised to an upright position in whch it may be used in drillingand per-forming other operations above the well; I

FIG. 3 is an end view of the mast in the upright position of FIG. 2,taken from the right thereof, and preparatory to being tilted;

FIG. 4 is another side elevation of the mast of FIGS. 1 to 3, but inwhich the mast has been tilted to a position for use as a crane boom inhandling'equipment laterally of the well location;

FIG. 5 is a sectional plan view of the mast in the tilted position ofFIG. 4, and taken substantially along broken line 55 of FIG. 4;

of the plat-form; and

FIG. 7 is a detailed side view of the lower end of the movable leg ofFIG. 6, and in a position released from securement with the platformdeck.

In accordance with the present invention, and with particular referenceto the illustrative embodiment of the drawings, there is provided a mast10 of substantially A frame construction so as to provide an open face(FIG. 3) and mounted upon a platform 11 for swinging movement about itslower end in a vertical plane transversely to said open face, between alowered, substantially horizontal position as shown in FIG. 1, anupright position as shown in FIGS. 2 and 3, and a tilted position, asshown in FIGS. 4 and 5. As can be seen from the drawings, the platform11 is disposed over a slot 28 (FIG. 5) toward one edge of a floatablebarge-mounted support 13, and a headrest 12 is carried upon another partof the support 13 inboard of slot '28 for supporting a part of the mastin its lowered position.

The lower end of the mast 10 is pivotally connected to brackets 14 onthe deck of the platform 11 and is be used in the handling of equipmentlaterally of the well I laterally supported in its upright position by apair of spaced apart stiff legs 15. As can be seen from the drawings,the stiff legs 15 are pivotally connected at their upper ends to themast 'at brackets 17 intermediate the upper and lower ends of the mastand releasably secured at their lower endsto brackets 16 on the deck ofthe platform so as to provide a rigid connection therebetween.

In a manner to .be described hereinafter, and in accordance with certainof the novel features of this invention, the stiff legs are also useablein raising and lowering as well as tilting the mast.

The illustrated mast, in so far as its raising mechanism is concerned,is of a type generally known in the field as a cantilever mast, whereinthe stiff legs 15 form,

- along with auxiliary legs 15a, atriangular support which isfixedly'mountable on the deck of the platform in the position of FIGS. 1and 2 of the drawings, wherein it is cooperable with a block and tacklemeans 18 suspended from the upper end of the mast for raising orlowering same. More particularly, a sling line 19 is extended be tweenthe pivotal joinder of the upper ends of legs and 15a formingthe-triangular supports and a hook on the traveling block 21 of theblock and tackle means 18. Also, a fast line 22 is guided over a sheavesupported upon a shaft 20a (FIG. 3) which connects the upper ends of thetriangular supports so as to extend between conventional drawworks 23 onthe platform and a crown block 24 at the upper end of the mast. With thesling line 19 and fast line 22 secured as described, the d-rawworks 23may be operated to take up on. the fast line 22 so as to swing the mastfrom the position of FIG. 1 into the position of FIG., 2, wherein it maybe secured by means of brackets 17 to the upper ends of the triangularsupport, as previously mentioned.

The block and tackle means 18 may conventionally include, in addition tothe drawworks 23, fast line 22, crown block 24, and traveling block 21,a deadline 26 which extends downwardly from a sheave on the crown blockto a point fixed with respect to the platform, such as at 27. As wellknown in the art, the drawworks 23 includes suitable power means forrotating a drum about which the fast line 22 may be wound forselectively raising or lowering the traveling block 21. In this manner,with the sling line 19 removed, the block and tackle means may be usedin conventional fashion in its upright position for drilling andperforming other operations above the well location.

It should be understood that many of the novel features of the presentinvention are not necessarily limited to the particular mastconstruction above-described and shown in the drawings. Although, forreasons which will be apparent from the description to follow, thisparticular type of mast is preferred, the method of this invention maybe carried out with other masts having an open face construction bymeans of which the block and tackle means may be swungfrom within themast in its upright position to a position laterally thereof in itstilted position, as shown in FIG. 4.

The support structure 13 is fixedly located with respect to a subsurfacelevel at an offshore location by means of supporting columns or piles 29which are driven securely into the subsurface beneath the water level30. Alternatively, the support may be any one of the other well knownmobile type structures employing, in the place of the piles 29, asubmergible hull or such a hull in combination with suitable piling. .Atany rate, the details of the supporting structure do not form part ofthe present invention, but merely illustrate an environment for whichthe invention is particularly well suited. In fact, it is contemplatedthat the mast of the present invention and'the novel method for usingsame may be employed with considerable utility on land wherein theplatform 11 would not be mounted at an offshore location.

As previously mentioned, the stiff raising legs are'also useable, incooperation with the hoisting apparatus, for swinging the mast betweenupright and tilted positions. Thus, the lower ends of the legs 15 arereleasable from their securement with brackets 16 and moveable acrossthe platform under the control of the drawworks 23 in a manner to swingthe mast as desired. More particularly, the lower ends of the raisinglegs are moveable away from brackets 16 in swinging the mast from itsupright to a tilted position in an opposite direction from its loweredposition.

As shown in FIG. 4, in the tiltedposition of the mast, the block andtackle means 18 is so located as to permit it to suspend equipmentlaterally of the well location as well as the support structure 13. Thusthe block and tackle means may, in the tilted position of the mast, be

used either prior to or after the well is drilled for setting wellheadprotective jackets and production platforms at the well location. Thus,with such equipment suspended from the traveling block when the mast isin the position of FIG. 4, another line (not shown) may be used to swingthe equipment laterally into the position desired. Obviously, in thedrilling of the well and performance of other operations thereabove, thehoisting apparatus may be used in the upright position of the mast in amanner well known in the art. For purposes of simplicity, and furthersince such operations are well known and do not perform a part of thepresent invention, certain of the equipment used in drilling the wellhas not been shown in the drawings.

" In its tilted position, the mast It) is laterally supported by one ormore flexible guy lines 31 extended between the upper end of'the mastand points '32 fixedly mounted upon the support structure 13, as shownin FIGS. l, '2 and 3. In the preferred form shown, a pair of such guylines are used, one on each side of the mast so, as to extend downwardlyand outwardly from their connections with the mast at the upper portionthereof such as from their connections with opposite sides of crownblock 24 as shown in FIG. 3. Such an arrangement provides a degree ofstability against swinging of the mast out of its vertical plane ofmovement. Obviously, the guy lines 31 are of sufficient strength as tolaterally support the mast in its tilted position and are of such lengthso that when extended by the tilted mast, they will support same in thedesired predetermined position.

As previously mentioned, in the upright position of the mast, the stiffleg 15 provides a rigid connection between the platform and a pointintermediate the upper and lower ends of the mast. According to thepresent invention, the rigid connection between the mast and platform isreleasable such that the Weight of the tilted mast and any loadsupported therefrom is transferred to the lateral support provided byguylines 31. In this manner, in the tilted position of the mast, the stifflegs 15 are rendered ineffective as force-transmitting members so thatthe mast is not loaded eccentricallydue to combined bending andcompression stresses. That is, it will be understood that unless therigid connection provided by the stiff legs 15 were renderedineffective, the mast in its tilted position would act as a cantileverbeam from the bracket 17 to its upper end and thus be subjected tobending stresses when loads-were supported-therefrom.

With particular reference now to the manner in which the stiff legs 15serve to swing the mast between upright and tilted positions, it can beseen from FIGS. 1 1504 that the lower ends of the stiff legs can beprovided with rollers 33, skids or the like, adapted to slide over'thedeck of the platform 11 upon release from thebracket 16, in a manner tobe described more fully hereinafter. The lower ends of the legs are alsoprovided with-parts 34 (see FIG. 7) to which a sling line 35 maybeattached for extension about sheaves 36 on the deck of theplatform andupwardly for attachment to the hook ofthe traveling block 21. Thisconnection between the block and tackle means and the lower ends ofstiff legs 15 permits the movement of such legs-to be controlled inswinging-the mast between upright and tilted positions. Thus, with thefast-line from the drawworks guided about sheave 38, as shown in FIG. 4,and VVlth' guy lines 31 of the desired length extended between the upperends ofthe mast and fixed points 32, the drawworks may be operated so asto ease off on the block and tackle means and thus permit the lower endsof the stiff legs to gradually move outwardly overthe deck of theplatform inswinging the mast to a tilted position. 4

As the mast is gradually moved to approximately its predetermined tiltedposition, the tension in the line 35 is released so that the weight ofthe mast is transferred to the guy lines 31 and the stiff legs 15 arerendered inoperative as force-transmitting members. -It'will'be-un=derstood then that with the lateral support for the mast in its tiltedposition" being connected thereto at its upper end, and with the loadsuspended from the mast by means of the traveling block as shown inbroken lines inFIG. 4, the mast will be loaded substantially incompression as a column only. Thus, it will be further understood thatimproved loading characteristics maybe obtained, in accordance with thisinvention, merely upon shifting of this lateral support from a pointadjacent brackets 17 to a point upwardly toward the upper end of themast. However, optimum results are obtained by connecting the lateralsupport provided by the guy lines 31 to the upper end of the mast sothat substantially all combined bending and -compression stresses areremoved.

The reason for sheaves 36 would appear obvious in that they enable theforces exerted by the lines 35 for controlling movement of the lowerends of the legs 15 to be directed along paths substantially coincidentwith the desired movement thereof. On the other hand, the sheave 38permits the line 22 connected between the crown block 24 and drawworks23 to be directed down the side of the mast opposite from'that fromwhich the traveling block swings upon tilting of the mast. This, ofcourse, enables a more desirable distribution of forces for raising andlowering the traveling block 21 in the tilted position of the mast. Itshould be understood, however, that the same purpose might beaccomplished by skidding the drawworks 23 over the deck of the platform11 from the position shown in FIG. 4 to a position on the opposite sideof the'brackets 14. Also, drawworks mounted as shown in' FIG. 4 may befound to interfere with suspendingejquipment laterally of the welllocation, and thus provideanother reason for skidding same.

Where themast is sufficiently open, sheave 38 need not be used duringtilting of the mast.

Suitablewinches' may be provided as shown at points 32 so that when themast has been tilted in a manner as described above, its position may beadjusted by means of the guy lines 31. Of course, in such a case, theoperation of the winches for the guy lines may be syncronized with oneanother in any suitable manner.

Still further, this means for tilting the mast may be used not only forthe purpose mentioned, but also in making the .mast plumb when theplatform upon which it is supported is not level with the earthssurface. This may be especially helpful in the case of offshore drillingwherein the supporting structure may not have settled into thesubsurface evenly or 'where'the subsurface itself is not level. 1 7

Apart from its usefulness in raising and lowering the mast, the stiffleg 15 provides a member of.minimum length for tilting the. mast, andthus reduces its overall cost of construction; Furthermore, intransferring the lateral support of the mast from a stiff orrigid'member, such as'the legs 15, to a flexible one such as the guylines 31, this method provides the tilted mast with a desiredflexibility forfunctioning as a crane boom.

To summarize this novel method of converting a mast of the general typedescribed from use in an upright position for drilling and performingother operations above a well location to use in a tilted position forhandling equipment laterally of the well location,'one or more 'guylines 31 of a length to limit swinging of the mast to a predeterminedtilted position are loosely'extended between the upper end of the mastand the fixed points 32. The sling line 35 is then extended from thehook on traveling block 21, about sheave 36, and to the attaching parts34 on the lower ends of stiff legs 15. Upon release of the securement(to be described) of the lower ends of the legs 15 from brackets 16 onthe deck of the platform 11, the'line 35 is gradually eased off soastopermitrollers 33 or skids to move over the deck of the platform.With the upper end of the legs 15 pivotally connected at brackets 17 topoints intermediate the upper and lower ends of the mast, this movementof the legs causes the mast'to swing about its pivotalconnection'withthe platform at brackets 14 and toward the predeterminedtilted position. At a time when the mast has approximately reached itspredetermined tilted position, the tension on the line 35 is releasedsuch that the mast extends the guy lines '31 and its weight isabsorbedthereby. Thus, the rigid connection provided by'legs 15 isreleased and the mast is positively connected to the platform 11 only atits lower pivotal connection, so that any load suspended from thetraveling block laterally of the well location will be transmittedthrough the pivotal connection to load the tilted mast as a column only.

Obviously, the mast is returned from its tilted to its upright positionby a reversal of the foregoing. That is, the-line 35 is extended betweenthe lower ends of stiff legs 15 and traveling block 21 so that whenthedrawworks is operated in a manner to gradually take up on the line 35,the rollers 33 are caused to move inwardly toward' the pivotalconnection of the mast until such time as they are disposed oppositebrackets 16 to permit the connection between the lower ends of the stifflegs and the brackets to be remade. Thus, themast will, in its uprightposition, again be laterally supported'by the stiff legs 15 whichprovide a rigid connection between an intermediate portion of the mastand the platform; Referring to FIGS. 6 and 7, the brackets 16 areprovided with openings therethrough and 'aresecured in spaced apartrelation to receive therebetween a plate 39 at the lower end of eachstifi leg. Each plate has hollow journals 40 extending from each sidethereof so that a pin 41 having a head 42 at one end and a rotatablelatch 43 at its opposite end may be extended through the openings in thebrackets 16 and the journals 40to secure the lower ends of the legs 15in the position shown in the drawings. Furthermore, the rollers 33 arerotatably mounted upon the plates 39 beneath journals 40 for rollingengagement with the deck of the platform. Parts 34 may merely comprisepins projecting outwardly from a rearward portion of the plates 39 so asto'receive a suitable connection 44'on the end of sling line 35.

It is contemplated that the movement of the lower .ends of stiff legs 15can be controlled or caused by means other than those specificallyillustrated in the drawings, Thus, a hydraulic ram or jack, a screw orother means may be used to supply the'necessary force for moving thestiff legs.

Fromthe foregoing it will be seen thatthis invention is one Well adaptedto attain all-.of the ends and objects hereinabove set forth, togetherwith other advantages which are obvious and which are inherent to themethod and apparatus.

It will be understood that certain features and su combinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not-in a limiting sense.

The invention having been described, what is claimed 1. In a method ofconverting a mast from use in an upright position in drilling andperforming other operations on a well to use in a tilted position inhandling equipment to one side of the: well location, wherein the mastis of a type mounted on'a platform for swinging movement in a verticalplane and laterally supported in its upright position by a leg providinga rigid connection between the platform and a point on the mastintermediate its upper and lower ends, the steps of mow ing one-end ofsaid leg along the platform to swing the mast from its upright positionto approximately a predetermined tiltedposition and during such movementof the leg employing it to provide lateral support for the mast,releasing the connection provided by said leg between the platform andmast, and laterally supporting the mast in its predetermined tiltedposition by a guy line connected between the upper end of the mast and apoint fixed with respect to the platform, whereby loads upon the mast insaid tilted position are prevented from being transmitted through saidleg.

2. In a method of converting a mast from use in an upright position indrilling and performing other operations on a well to use in a tiltedposition in handling equipment to one side of the well location, whereinthe mast is of a type mounted on a platform for swinging movement in avertical plane and laterally supported in its upright position by a legproviding a rigid connection etween the platform and a point on the mastintermediate its upper and lower ends, the steps of connecting a guyline between the upper end of the mast and a point fixed with respect tothe platform for limiting swinging of the mast from its upright positionto a predetermined tilted position, controllably moving one end of saidleg along the platform in such a manner as to swing the mast intoapproximately its predetermined tilted position while employing the legto provide lateral support for the mast during its movement to saidtilted position, and releasing the rigid connection between the mast andplatform to permit the mast to extend the guy line and prevent loadsupon the mast in said tilted position from being transmitted throughsaid leg.

3. Apparatus for use in drilling and performing other operations on awell and handling equipment to oneside thereof, comprising a platform, amast having an open face and mounted on the platform for swingingmovement in one direction in a vertical plane from an upright to atilted position, block and tackle means carried from the upper end ofthe mast for suspending equipment above the well location in the uprightposition of the mast and to one side of the well location in the tiltedposition thereof, a stiff leg pivotally connected at its upper end to apoint intermediate the upper and lower ends of the mast, means forconnecting the lower end of the leg to the platform to provide a lateralsupport for the mast in its upright position, said last mentionedconnecting means being releasable, said mast when in said uprightposition being biased toward tilted position against the supportingaction of said leg, means connectible between the lower end of the legand said block and tackle means whereby upon release of the connectingmeans at the lower end of the leg such lower end can be controllablymoved away from. the mast and along. the platform by manipulation of theblock and tackle means to move the mast to tilted position while beingsupported by the leg, and a guy line connected between the upper end ofthe mast and a point fixed with respect to the platform to providelateral support for the mastwhile in tilted position.

4; Apparatus of the character defined in claim 3, including rollers onsaid lower end of the leg engageable with the platform upon movementthereacross.

5. Apparatus for use in drilling and performing other operations on, anoffshore well from a barge-mounted support and for handling equipment atone side of the support, comprising a platform above a drilling slot inthe support, a mast having means for suspending equipment therefrom,means mounting the mast on the-platform for swinging movement in avertical plane,,means for swinging the mast in one direction from asubstantially horizontal to an upright drilling position, meansincluding a stiff leg connected between the mast and platform when themast is in its upright position and supporting the mast in its uprightposition in which equipment is suspended above the well location fordrilling and performing said other operations on. the well through saiddrilling slot, said mast when in such upright position being biasedtoward tiltingin said one direction against the action of said stifileg, said platform including support means extending in said onedirection. from the stiff legs connection with the platform forsupportably engaging the lower end of the stiff leg when said lower endis moved in said one direction, means for controllably moving the lowerend of the stiff leg in said one direction along and in engagement withsaid support means so as to swing the stiif leg about its upper end totilt the mast in said one direction from its upright to a tiltedposition while employing the leg to provide lateral support for the mastduring its movement to its tilted position and upon the mast reachingits tilted position, being releasable from providing said lateralsupport to the mast, and other supporting means connected between themast adjacent the upper 'end thereof and a point fixed with respect tothe platform to support the mast in its tilted position.

6. Apparatus for use indrilling and performing other operations on anoflishore well from a barge-mounted support and handling equipment atone side of the support, comprising a platformabove a drilling slot inthe support, a mast having means for suspending equipment therefrom,means mounting the mast on the platform for swinging movement in onedirection in a vertical plane between a substantially horizontalposition and an upright position for suspendingequipment above the welllocation, means for moving the mast between said substantiallyhorizontal and upright positions, means including a stifi leg connectedbetween the platform and the mast intermediate the masts ends forsupporting the mast in said'upright position for drilling andperformingsaid other operations on the well through said drilling slot,said mast when in its upright position having its center of gravitydisposed to bias'it toward swinging in said one direction against theaction of said supporting means, said platform including support meansextending in said one direction from the stiff legs connection with theplatform for supportably engaging the lower end of the stifif leg whensaid lower end is moved in said one direction, means for controllablymoving the lower end of the stiff leg along and in engagement with thesupport means and away from the mast while the leg is providing lateralsupport for the mast to swing the mast in said one direction from itsupright position to a tilted position for disposing the suspending meansto one side of the well location, and cable means connected between themast adjacent its upper end and a point fixed with respect to theplatform for supporting the mast in its tilted position.

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